EP4206366A1 - Procédé de fabrication de polycristal de sic - Google Patents
Procédé de fabrication de polycristal de sic Download PDFInfo
- Publication number
- EP4206366A1 EP4206366A1 EP21861712.4A EP21861712A EP4206366A1 EP 4206366 A1 EP4206366 A1 EP 4206366A1 EP 21861712 A EP21861712 A EP 21861712A EP 4206366 A1 EP4206366 A1 EP 4206366A1
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- EP
- European Patent Office
- Prior art keywords
- sic
- stress
- polycrystal
- seed crystal
- manufacturing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 57
- 229910010271 silicon carbide Inorganic materials 0.000 claims abstract description 177
- 239000013078 crystal Substances 0.000 claims abstract description 66
- 238000000034 method Methods 0.000 claims abstract description 33
- 239000000758 substrate Substances 0.000 claims abstract description 29
- 238000000859 sublimation Methods 0.000 claims abstract description 14
- 230000008022 sublimation Effects 0.000 claims abstract description 14
- 238000001953 recrystallisation Methods 0.000 claims abstract description 12
- 229910021431 alpha silicon carbide Inorganic materials 0.000 claims abstract description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 40
- 229910052757 nitrogen Inorganic materials 0.000 claims description 20
- 229910052751 metal Inorganic materials 0.000 claims description 19
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 10
- 229910052796 boron Inorganic materials 0.000 claims description 10
- 239000010936 titanium Substances 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- 229910052706 scandium Inorganic materials 0.000 claims description 2
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 claims description 2
- 229910052719 titanium Inorganic materials 0.000 claims description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 148
- 238000009434 installation Methods 0.000 description 20
- 239000002994 raw material Substances 0.000 description 13
- 239000007789 gas Substances 0.000 description 10
- 238000002844 melting Methods 0.000 description 10
- 230000008018 melting Effects 0.000 description 10
- 230000001681 protective effect Effects 0.000 description 10
- 239000012212 insulator Substances 0.000 description 8
- 239000010453 quartz Substances 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 239000003574 free electron Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 229910002804 graphite Inorganic materials 0.000 description 4
- 239000010439 graphite Substances 0.000 description 4
- 125000004429 atom Chemical group 0.000 description 3
- 230000003139 buffering effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- NFFIWVVINABMKP-UHFFFAOYSA-N methylidynetantalum Chemical compound [Ta]#C NFFIWVVINABMKP-UHFFFAOYSA-N 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910003468 tantalcarbide Inorganic materials 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
- C30B23/02—Epitaxial-layer growth
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B28/00—Production of homogeneous polycrystalline material with defined structure
- C30B28/12—Production of homogeneous polycrystalline material with defined structure directly from the gas state
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/36—Carbides
Definitions
- the present disclosure relates to a method for manufacturing a SiC polycrystal.
- a known existing method for manufacturing SiC polycrystals includes defining a space between the ceiling of a graphite vessel and the rear surface of a seed crystal by disposing the seed crystal on a shelf of the graphite vessel, disposing Si and C atom sources inside the graphite vessel, heating a furnace, and promoting gas phase transport from the Si and C atom sources to the seed crystal while making it unlikely that the rear surface of the seed will contact the ceiling by evacuating the induction furnace and directing a gas flow from below the seed crystal through the regions around the seed crystal to the center of the space between the ceiling of the graphite vessel and the seed crystal (refer to, for example, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2016-508948 ).
- the present disclosure provides a SiC polycrystal manufacturing method based on a sublimation recrystallization method using a SiC seed crystal.
- a polycrystalline SiC substrate that is a SiC polycrystal produced by a sublimation recrystallization method and contains a greater amount of ⁇ -SiC than ⁇ -SiC is used as the SiC seed crystal.
- SiC polycrystals having higher thermal conductivity have been demanded.
- the thermal conductivity of manufactured SiC polycrystals can be improved from what was previously possible.
- FIG. 1 is a cross section of the manufacturing apparatus 100 according to this embodiment taken along the vertical direction (crystal growth direction).
- the manufacturing apparatus 100 is used to manufacture a SiC polycrystal C using a sublimation recrystallization method.
- the manufacturing apparatus 100 includes a vessel 1, a SiC seed crystal Cs, and a coil 2.
- the manufacturing apparatus 100 further includes a heat insulator 3 and a quartz tube 4.
- the vessel 1 includes a crucible 11, a stress-buffering sheet 12, and a lid 13.
- the crucible 11 includes a crucible body 111 and a support member 112.
- the crucible body 111 includes a bottom part 111a and a side wall 111b, and is open at the top thereof.
- the material of the crucible body 111 according to this embodiment is carbon.
- the support member 112 is a cylindrical member that extends in the vertical direction.
- the material of the support member 112 according to this embodiment is carbon.
- a plan view outline of the support member 112 is approximately the same as a plan view outline of the crucible. Therefore, the support member 112 can be placed on the top surface of the crucible 11.
- An inner wall surface of the support member 112 includes a support portion 112a.
- the support portion 112a protrudes in the direction of a central axis of the support member 112.
- the support portion 112a may be provided along the entire periphery of the inner wall surface, or a plurality of the support portions 112a may be provided at intervals from each other.
- the crucible 11 may also be configured such that the crucible body and the support member are integrated with each other.
- the stress-buffering sheet 12 a member on which the SiC polycrystal C grows on the bottom surface thereof.
- the material of the stress-buffering sheet 12 according to this embodiment is carbon.
- the stress-buffering sheet 12 is placed on the support portion 112a of the crucible 11.
- the thickness of the stress-buffering sheet 12 according to this embodiment lies in a range of 0.3 to 2.0 mm.
- the stress-buffering sheet 12 may be provided with a high melting point protective film 12a on the bottom surface thereof.
- the high melting point protective film 12a is, for example, composed of tantalum carbide (TaC).
- any of a variety of existing known techniques can be used to form the high melting point protective film 12a.
- the lid 13 includes a lid body 131 and a projection 132.
- a plan view outline of the lid body 131 is substantially the same as a plan view outline of the crucible 11 (support member 112). Therefore, the lid body 131 can be placed on the top surface of the crucible 11.
- the projection 132 projects from a surface (bottom surface) of the lid body 131 facing the stress-buffering sheet 12 towards a region (underside) of the stress-buffering sheet 12 where the SiC polycrystal C will grow.
- the projection 132 projects with a width corresponding to that of the region on the bottom surface of the stress-buffering sheet 12 where the SiC polycrystal C will grow.
- the "region where the SiC polycrystal C will grow" refers to the region of the bottom surface of the stress-buffering sheet 12 that is not overlapped by the support portion 112a (i.e., is not shielded by the support portion 112a and is visible when looking upward from inside the crucible body 111).
- the projection 132 according to this embodiment is located within the region where the SiC polycrystal C will grow and overlaps 80% or more of that region when viewed in plan view.
- a side surface 132a of the projection 132 may be inclined so that the width of the projection 132 decreases with increasing proximity to the lid body 131 (increasing separation from the stress-buffering sheet 12).
- the side surface 132a of the projection 132 may be recessed.
- the lid 13 may include multiple projections 132. This would increase the area of the surface of the lid 13 on which SiC gas can be adsorbed and the SiC gas would be more likely to recrystallize on the lid 13. Therefore, SiC would be less likely to recrystallize on the top surface of the stress-buffering sheet 12.
- a space is formed between the lid 13 (projection 132) placed on the crucible 11 and the stress-buffering sheet 12.
- the gap between the projection 132 and the stress-buffering sheet 12 is greater than the amount by which the stress-buffering sheet 12 will deform while the SiC polycrystal C is growing.
- the distance between the projection 132 and the stress-buffering sheet 12 prior to crystal growth is such that an upper edge (peripheral edge) of the stress-buffering sheet 12, which bends and deforms so as to be downwardly convex during the growth of SiC polycrystal C, does not contact the bottom surface of the projection 132.
- the SiC seed crystal Cs is a polycrystalline SiC substrate.
- Polycrystalline SiC substrates are SiC polycrystals produced using a sublimation recrystallization method, and contain a greater amount of ⁇ -SiC (hexagonal crystals) than ⁇ -SiC (cubic crystals).
- the polycrystalline SiC substrate may contain only ⁇ -SiC (does not need to contain ⁇ -SiC).
- the polycrystalline SiC substrate also contains nitrogen (N) as a trace component (impurity).
- Nitrogen is mixed in during the manufacture of the polycrystalline SiC substrate.
- the concentration of nitrogen in the polycrystalline SiC substrate according to this embodiment is kept within a range of 5 ⁇ 10 15 to 5 ⁇ 10 17 atoms/cm 3 (0.1 to 10 ppm).
- the polycrystalline SiC substrate further contains at least one out of boron (B) and aluminum (Al) as a trace component.
- boron and aluminum are mixed in (rather than added) during the manufacture of the polycrystalline SiC substrate.
- the concentration of boron in the polycrystalline SiC substrate according to this embodiment is controlled to be in a range of 5 ⁇ 10 15 to 5 ⁇ 10 17 atoms/cm 3 (0.1 to 10 ppm).
- the concentration when aluminum is included as a trace component, or when both boron and aluminum are included as trace components, is the same as or similar to the above concentration.
- the polycrystalline SiC substrate contains at least one out of the metallic elements vanadium (V), scandium (Sc), and titanium (Ti) as a trace component.
- the metallic elements are added during the manufacture of the polycrystalline SiC substrate.
- the concentration of the metallic elements in the polycrystalline SiC substrate according to this embodiment is in a range of 1 ⁇ 10 16 to 8 ⁇ 10 17 atoms/cm 3 (0.2 to 17 ppm).
- the concentration of metallic elements in the polycrystalline SiC substrate is higher than that of nitrogen.
- the polycrystalline SiC substrate according to this embodiment has a low concentration of nitrogen, which causes free electrons to be generated, and contains a greater amount of metallic elements than nitrogen.
- the donor level of nitrogen is close to the conduction band of SiC. Therefore, nitrogen typically attempts to emit an electron e into the conduction band.
- the acceptor levels of the metallic elements exist in the vicinity of the donor level of nitrogen and are closer to the valence band than the donor level of nitrogen. Therefore, an electron e in the donor level of nitrogen moves not to the conduction band but to the acceptor level of a metallic element, which is more stable than the conduction band.
- the electrons e of nitrogen are supplemented by the metallic element, and the electrons e no longer flow through the conduction band of SiC.
- the boron contained in the SiC crystal has an acceptor level in the vicinity of the valence band of SiC, as illustrated in FIG. 4 . Therefore, boron steals an electron e from the valence band. As a result, a hole h (positive hole) is created in the valence band (Step S 1).
- Step S2 Due to the creation of the hole h in the valence band, which has lower energy than the conduction band, an electron e emitted from the donor level of nitrogen to the conduction band is readily incorporated into the valence band (Step S2), and the electron e no longer flows through the conduction band of SiC.
- the concentration of boron is higher than the concentration of nitrogen, an excess of holes will be generated in the valence band of SiC.
- the metallic element has a donor level that is closer to the valence band than an acceptor level, as illustrated in FIG. 4 . Therefore, a hole h in the valence band moves to the donor level of the metallic element (Step S3). In this way, the holes h are supplemented by the metallic element and the holes h do not move through the conduction band of SiC. This mechanism is also the reason why the SiC seed crystal Cs according to this embodiment has high insulating properties.
- the concentration of the metallic elements in the polycrystalline SiC substrate is preferably higher than the difference between the concentrations of nitrogen and boron.
- the thus-configured SiC seed crystal Cs is positioned on the bottom surface of the stress-buffering sheet 12 as illustrated in FIG. 1 .
- the stress-buffering sheet 12 or SiC seed crystal Cs includes the high melting point protective film 12a
- the polycrystalline SiC substrate is positioned on the bottom surface of the high melting point protective film 12a.
- An a-axis of the SiC seed crystal Cs is oriented along the growth direction (vertical direction) of the SiC polycrystal C as illustrated in FIG. 5 .
- the polycrystalline SiC substrate may be subjected to a sealing process so as to close micropipes P.
- the SiC seed crystal Cs may have a high melting point protective film on its top surface instead of the stress-buffering sheet 12.
- the heat insulator 3 covers the vessel 1.
- the quartz tube 4 surrounds heat insulator 3 from the outside.
- the quartz tube 4 is a double tube consisting of an inner tube 41 and an outer tube 42.
- Water can be passed between the inner tube 41 and the outer tube 42.
- the quartz tube 4 may instead be a single-layer tube.
- the coil 2 is used to heat the vessel 1 by high-frequency induction heating.
- the coil 2 surrounds the quartz tube 4 from the outside.
- the vessel 1 may be heated by resistance heating using a heater instead of the coil 2. When resistance heating is used, the vessel 1 is heated by disposing the resistance heating inside the quartz tube 4.
- FIGs. 6A to 6E , FIG. 7A, and FIG. 7B are sectional views illustrating steps of the method for manufacturing the SiC polycrystal C.
- FIG. 8A is a sectional view of a SiC polycrystal manufactured using a manufacturing method of the related art taken along the growth direction.
- FIG. 8B is a sectional view of the SiC polycrystal C manufactured using a manufacturing method according to the present disclosure taken along the growth direction.
- FIG. 9A is a sectional view of a SiC seed crystal and a SiC polycrystal manufactured using the manufacturing method of the related art taken along the growth direction.
- FIG. 9B is a sectional view of a SiC seed crystal and the SiC polycrystal C manufactured using the manufacturing method according to the present disclosure taken along the growth direction.
- the method for manufacturing the SiC polycrystal C includes a crucible preparation step, a raw material feeding step, a seed crystal attaching step, a stress-buffering sheet installation step, a lid installation step, and a growth step.
- the method for manufacturing the SiC polycrystal C according to this embodiment further includes a support member installation step, an evacuation step, and a cooling/removal step.
- the crucible 11 including the support portion 112a on the inner surface thereof is prepared.
- the process moves on to the raw material feeding step.
- SiC polycrystal raw material M SiC polycrystal powder and metallic elements to be added as trace components
- the method for manufacturing the SiC polycrystal C according to this embodiment moves on to the support member installation step.
- the support member 112 is installed on the crucible body 111 into which the raw material M has been introduced.
- the crucible 11 is a crucible in which the crucible body and the support member are integrated with each other, this support member installation step is not necessary.
- the polycrystalline SiC substrate is attached to the bottom surface of the stress-buffering sheet 12 as the SiC seed crystal C S .
- the polycrystalline SiC substrate is attached to the bottom surface of the high melting point protective film 12a.
- the SiC seed crystal Cs is disposed such that the a-axis of the SiC seed crystal Cs is oriented along the growth direction of the SiC polycrystal C.
- the stress-buffering sheet 12 which has a region on the lower surface thereof where the SiC polycrystal C will grow, is provided on the support portion 112a of the crucible 11.
- the peripheral portion of the stress-buffering sheet 12 is placed on the support portion 112a of the support member 112.
- the thickness of the stress-buffering sheet 12 is in a range of 0.3 to 2.0 mm. In this way, the rigidity of the stress-buffering sheet 12 is maintained and a situation in which the growing SiC polycrystal C falls off can be avoided.
- stress-buffering sheet 12 may be provided on the support portion 112a at a timing before installing the support member 112 on the crucible body 111.
- the support member 112 may be placed on the crucible body 111 after placing the stress-buffering sheet 12 on the support portion 112a of the support member 112.
- the SiC seed crystal Cs may be attached to the bottom surface of the stress-buffering sheet 12 after installing the stress-buffering sheet 12 on the support portion 112a of the crucible 11, but before installing the support member on the crucible body 111.
- the lid 13 including the projection 132 is installed on the crucible 11.
- the lid 13 is placed on the support member 112 so that the projection 132 is positioned inside the support member 112.
- the projection 132 projects towards the region where the SiC polycrystal C will grow on the stress-buffering sheet 12.
- the gap between the projection 132 and the stress-buffering sheet 12 is larger than the amount by which the stress-buffering sheet 12 will deform while the SiC polycrystal C is growing.
- the width of the above-described space is secured by adjusting the distance between the top edge of the crucible 11 and the top surface of the support portion 112a, or the thickness of the projection 132 of the lid 13.
- the vessel 1 is disposed inside the heat insulator 3 of the manufacturing apparatus 100.
- the interior of the manufacturing apparatus 100 is evacuated and filled with an inert gas.
- the raw material M in the crucible 11 is sublimated so as to grow the SiC polycrystal C on the bottom surface of stress-buffering sheet 12.
- a high-frequency alternating current is energized in the coil 2.
- high-density eddy currents are generated in the vessel 1.
- the vessel 1 is then heated up by the eddy currents up to the temperature at which the raw material M sublimates.
- SiC gas G produced by the sublimation of the raw material M rises to the height of the stress-buffering sheet 12 and recrystallizes on the bottom surface of the stress-buffering sheet 12.
- Some of the SiC gas G produced by the sublimation of the raw material M passes through the gap between the support portion 112a of the crucible 11 and the stress-buffering sheet 12 and flows around to the side where the lid 13 is located.
- the SiC gas G that has flowed around to the side where the lid 13 is located recrystallizes mainly on the side surface 132a of the projection 132. This makes it less likely that the SiC will recrystallize on the top surface of the stress-buffering sheet 12.
- the stress buffering performance of the stress-buffering sheet 12 is maintained during the growth of the SiC polycrystal C, and the stress contained in the manufactured SiC polycrystal C is reduced from what was previously possible.
- the projection 132 of the lid 13 is located within the region where the SiC polycrystal C grows and overlaps 80% or more of that region when viewed in plan view. This makes it less likely for the SiC to recrystallize in numerous regions on the top surface of the stress-buffering sheet 12 during the growth step described above. As a result, a region where the stress-buffering sheet 12 can deform for the purpose of stress buffering can be sufficiently secured.
- the surface area of the projection 132 is increased. This increases the amount of adsorption of the SiC gas that has flowed around to the side where the lid 13 is located during the growth step, and therefore it becomes less likely for the SiC gas that has flowed around to the side where the lid 13 is located to reach the top surface of the stress-buffering sheet 12.
- the space between the projection 132 and the stress-buffering sheet 12 according to this embodiment is larger than the amount of deformation of the stress-buffering sheet 12 that occurs while the SiC polycrystal C is growing. Therefore, in the growth step, further deformation of the deformed stress-buffering sheet 12 resulting from the stress-buffering sheet 12 contacting the projection 132 is obstructed, and degradation of the stress buffering function can be avoided.
- the stress-buffering sheet 12 is only placed on the support portion 112a of the crucible 11. This makes it more difficult for heat to be transferred from the crucible 11 to stress-buffering sheet 12 during the growth step, and this results in a uniform temperature distribution in planar directions (horizontal directions) of the stress-buffering sheet 12. As a result, flat SiC polycrystals C can be manufactured and the product yield is improved.
- the SiC seed crystal Cs is a SiC polycrystal produced by the sublimation recrystallization method and contains a greater amount of ⁇ -SiC than ⁇ -SiC. Therefore, a SiC polycrystal C (ingot) having few grain boundaries and high thermal conductivity can be manufactured from the initial stage of growth.
- SiC seed crystal Cs When the SiC seed crystal Cs is attached to the bottom surface of the high melting point protective film 12a, Si diffusing into the stress-buffering sheet 12 during the growth of SiC polycrystal C is reduced. Therefore, defects are less likely to occur in the growing SiC polycrystal C.
- the SiC seed crystal Cs has a low concentration of nitrogen, which generates free electrons, and also contains a greater amount of metallic elements, which trap free electrons, than nitrogen, and therefore has a low concentration of free electrons.
- the properties of the SiC polycrystal C that is grown depend on the properties of the SiC seed crystal Cs.
- the raw material M also contains metallic elements for the purpose of reducing the concentration of free electrons. Therefore, a SiC polycrystal C having high insulation properties can be grown from the SiC seed crystal Cs.
- the a-axis of the SiC seed crystal Cs according to this embodiment is oriented along the growth direction of the SiC polycrystal C, as described above.
- the micropipes P are less likely to occur in a direction along the a-axis. Therefore, as the SiC polycrystal C grows, the micropipes P bend in a direction along the c-axis, which is perpendicular to the crystal growth direction, as illustrated in FIG. 8B . As a result, a SiC polycrystal C can be obtained that has fewer micropipes P that penetrate in the direction in which the crystal grows.
- the micropipe P will continue into the inside of the SiC polycrystal C growing from the surface of the SiC seed crystal Cs, as illustrated in FIG. 9A .
- the temperature inside the manufacturing apparatus 100 is lowered in stages.
- the vessel 1 is removed from inside the heat insulator 3, the stress-buffering sheet 12 is removed from the crucible 11, and the SiC polycrystal is removed from the stress-buffering sheet 12.
- the SiC seed crystal Cs used in the SiC polycrystal manufacturing method described above is produced using a sublimation recrystallization method, and therefore has a larger crystal grain size and fewer grain boundaries (higher thermal conductivity) than crystals produced using a CVD method of the related art.
- the SiC seed crystal Cs contains a greater amount of ⁇ -SiC, which has higher thermal conductivity, than ⁇ -SiC.
- SiC crystals produced using seed crystals depend on the properties of the seed crystals. Therefore, a SiC polycrystal C manufactured using the SiC seed crystal Cs according to this embodiment has few grain boundaries and contains a larger amount of ⁇ -SiC.
- the thermal conductivity of the manufactured SiC polycrystal can be improved from what was previously possible.
- the vessel 1 is a vessel that can be used to manufacture a SiC polycrystal C by a sublimation recrystallization method using a seed crystal, the vessel 1 is not particularly limited.
- the lid 13 does not need to include the projection 132.
- the stress-buffering sheet 12 may be attached to the lid 13 in the vessel 1.
- the vessel 1 does not need to include the stress-buffering sheet 12.
- the SiC seed crystal Cs may be directly attached to the lid 13 or the support member 112.
- the present disclosure can be used in a method for manufacturing a SiC polycrystal.
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- Crystallography & Structural Chemistry (AREA)
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- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2020144558 | 2020-08-28 | ||
PCT/JP2021/031503 WO2022045291A1 (fr) | 2020-08-28 | 2021-08-27 | Procédé de fabrication de polycristal de sic |
Publications (1)
Publication Number | Publication Date |
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EP4206366A1 true EP4206366A1 (fr) | 2023-07-05 |
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Application Number | Title | Priority Date | Filing Date |
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EP21861712.4A Pending EP4206366A1 (fr) | 2020-08-28 | 2021-08-27 | Procédé de fabrication de polycristal de sic |
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US (1) | US20230357955A1 (fr) |
EP (1) | EP4206366A1 (fr) |
JP (1) | JPWO2022045291A1 (fr) |
CN (1) | CN116018431A (fr) |
WO (1) | WO2022045291A1 (fr) |
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---|---|---|---|---|
SE520968C2 (sv) * | 2001-10-29 | 2003-09-16 | Okmetic Oyj | Högresistiv monokristallin kiselkarbid och metod för dess framställning |
JP2005311261A (ja) * | 2004-04-26 | 2005-11-04 | Nippon Steel Corp | 炭化珪素製放熱板 |
JP4197178B2 (ja) * | 2005-04-11 | 2008-12-17 | 株式会社豊田中央研究所 | 単結晶の製造方法 |
US7608524B2 (en) * | 2005-04-19 | 2009-10-27 | Ii-Vi Incorporated | Method of and system for forming SiC crystals having spatially uniform doping impurities |
JP6619874B2 (ja) * | 2016-04-05 | 2019-12-11 | 株式会社サイコックス | 多結晶SiC基板およびその製造方法 |
-
2021
- 2021-08-27 WO PCT/JP2021/031503 patent/WO2022045291A1/fr unknown
- 2021-08-27 EP EP21861712.4A patent/EP4206366A1/fr active Pending
- 2021-08-27 CN CN202180053215.8A patent/CN116018431A/zh active Pending
- 2021-08-27 US US18/043,094 patent/US20230357955A1/en active Pending
- 2021-08-27 JP JP2022545730A patent/JPWO2022045291A1/ja active Pending
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WO2022045291A1 (fr) | 2022-03-03 |
CN116018431A (zh) | 2023-04-25 |
US20230357955A1 (en) | 2023-11-09 |
JPWO2022045291A1 (fr) | 2022-03-03 |
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